package miggy.cpu.instructions;

import miggy.api.cpu.Size;
import miggy.api.cpu.DecodedInstruction;
import miggy.cpu.DecodedInstructionImpl;
import miggy.api.cpu.InstructionSet;
import miggy.SystemModel;
import miggy.api.cpu.Instruction;
import miggy.cpu.operands.OperandFactory;

/*
//  Miggy - Java Amiga MachineCore
//  Copyright (c) 2008, Tony Headford
//  All rights reserved.
//
//  Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
//  following conditions are met:
//
//    o  Redistributions of source code must retain the above copyright notice, this list of conditions and the
//       following disclaimer.
//    o  Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
//       following disclaimer in the documentation and/or other materials provided with the distribution.
//    o  Neither the name of the Miggy Project nor the names of its contributors may be used to endorse or promote
//       products derived from this software without specific prior written permission.
//
//  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
//  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
//  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
//  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
//  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
//  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
//  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// $Revision: 21 $
*/
public class LINK implements Instruction
{
	public final void register(InstructionSet set)
	{
		int base = 0x4e50;
		for(int reg = 0; reg < 8; reg++)
		{
			set.add(base + reg, this);
		}
	}

	public int execute(int opcode)
	{
		int sreg = (opcode & 0x007);

		//signed displacement
		int displacement = (short)SystemModel.CPU.fetch(Size.Word);

		//push the address reg
		SystemModel.CPU.push(SystemModel.CPU.getAddrRegister(sreg), Size.Long);

		//copy the stack pointer to the address reg
		int sp = SystemModel.CPU.getAddrRegister(7);
		SystemModel.CPU.setAddrRegister(sreg, sp);

		//add the displacement to the stack pointer
		SystemModel.CPU.setAddrRegister(7, sp + displacement);
		return 16;
	}

	public final DecodedInstruction disassemble(int address, int opcode)
	{
		Size size = Size.Word;
		DecodedInstructionImpl di = new DecodedInstructionImpl("link", opcode, address, size);

		di.setSrc(OperandFactory.addrReg(opcode & 0x007));
		//test: changed to peek
		di.setDst(OperandFactory.displacement((short)SystemModel.MEM.peek(address + 2, Size.Word), size));
		return di;
	}
}
